Luminescent panel

ABSTRACT

A luminescent panel includes a transparent substrate, a first transparent electrode provided on the transparent substrate, a luminescent layer provided on the first transparent electrode, and a second transparent electrode provided on the luminescent layer. A reflecting film provided on the second electrode, reflects light emitted from the luminescent layer through the second transparent electrode and causes the reflected light to outwardly emit from the transparent substrate.

TECHNICAL FIELD

[0001] The present invention relates to a luminescent panel including anoptical member which improves an emitting efficiency.

BACKGROUND ART

[0002] Generally, since an EL element is a self-luminous type element,it is used as a backlight in a liquid crystal display, a light source ina printer head, a segment in a segment type display, a pixel in a matrixtype display and others. In particular, a display in which the ELelement functions as a pixel achieves a wide field angle, high contrast,an excellent visual recognition property, a low power consumption, agood shock resistance and others. As the EL elements, there are aninorganic EL element which is a thin film structure in which insulatingfilms are interposed between an EL layer using an inorganic compound asa luminescent material and a pair of electrodes, and an organic ELelement which is a laminated structure using an organic compound as aluminescent material.

[0003]FIG. 22 shows a structure of a typical luminescent panel usingorganic EL elements. A luminescent panel 901 is constituted bysequentially laminating an anode electrode 903, an organic EL layer 904including a luminescent material and a cathode electrode 905 on onesurface 902a of a transparent substrate 902. The organic EL layer 904may have a three-layer structure including a hole transport layer, aluminescent layer and an electron transport layer laminated on thecathode electrode 903 in the mentioned order, a two-layer structureconsisting of an electron hole transport layer and a luminescent layerfrom the side of the anode electrode 903 in the mentioned order, asingle-layer structure consisting of a luminescent layer, or a laminatedstructure that transport of electrons or electron holes is interposedbetween appropriate layers in the former layer structures.

[0004] In the luminescent panel 901, when a forward bias voltage isapplied between the anode electrode 903 and the cathode electrode 905,the electron holes are injected into the organic EL layer 904 from theanode electrode 903, and the electrons are injected into the organic ELlayer 904 from the cathode electrode 905. When the electron holes andthe electrons are transported into the organic EL layer 904 and theelectron holes and the electrons are re-combined in the organic EL layer904, excitons are generated, and a fluorescent material in the organicEL layer 904 is excited by the excitons whereby light is generated inthe organic EL layer 904.

[0005] Generally, the luminescent panel 901 uses the anode electrode 903as a transparent electrode, and the light is emitted toward the outsidefrom the other surface 902 b of the transparent substrate 902. At thismoment, since the light emitted from the organic EL layer 904 spreads ina radial pattern, the light emitting efficiency is improved in theluminescent panel 901 by providing the light blocking effect to thecathode electrode 905.

[0006] Since the light does not have the directivity in the luminescentpanel 901 and the light emitted from the organic EL layer 904 spreads ina radial pattern, a part of the light passing through the transparentsubstrate 902 is scattered in the transparent substrate 902, therebyreducing the light emitting efficiency from the transparent substrate902 to the outside.

[0007] Further, when the luminescent panel 901 is used in a matrix typedisplay, since the light emitted from the organic EL layer 904 spreadsin a radial pattern, it is hard to sufficiently increase the contrast ofa display screen in the front face direction.

[0008] Thus, the present invention is advantageous in increasing thelight emitting efficiency of the light emission panel by a lightemission element such as an organic EL element forming a laminatedstructure laminated on a transparent substrate and providing thedirectivity to light emission of a luminescent panel.

DISCLOSURE OF INVENTION

[0009] According to one aspect of the present invention, there isprovided a luminescent panel comprising:

[0010] a transparent substrate;

[0011] a first transparent electrode provided on one surface of thetransparent substrate;

[0012] a luminescent layer provided on the first transparent electrode;

[0013] a second transparent electrode provided on the to luminescentlayer, at least one pixel being defined by the first transparentelectrode, the luminescent layer and the second transparent electrode;and

[0014] a reflecting film which reflects light radiated from theluminescent layer through the second transparent electrode and causesthe reflected light to outgo from the transparent substrate.

[0015] In this luminescent panel, when the luminescent layer emits thelight, a part of the light is transmitted through the first electrodeand the transparent substrate as it is and outgoes from the othersurface of the transparent substrate. On the other hand, the remainingpart of the light is transmitted through the second electrode and thenreflected on the reflecting film. The reflected light is transmittedthrough the second electrode, the luminescent layer, the first electrodeand the transparent substrate, and outgoes from the other surface of thetransparent substrate. Here, the reflecting film need not closelycontact the luminescent layer as the second electrode. That is, when theluminescent layer is flat, the second electrode film must be also formedflatly, whereas the reflecting film can be set to an arbitrary shapeirrespective of the shape of the luminescent layer. Therefore, since thereflecting film can arbitrarily control the reflected light, theemitting efficiency of the light from the transparent substrate side canbe improved.

[0016] The reflecting film functions as a concave mirror when it isformed to have a concave portion, and the front face brightness can beimproved in particular. Also, it is possible to perform display with theextremely high contrast ratio with respect to a viewer from the frontside. In particular, when this luminescent panel is used as a personalsmall panel, visual recognition is performed almost only from the frontside, which is very effective. Further, in order to readily define theshape of the reflecting film, a lens may be provided on the inner sideor the outer side of the reflecting film.

[0017] Additional objects and advantages of the invention will be setforth in the description which follows, and in part will be obvious fromthe description, or may be learned by practice of the invention. Theobjects and advantages of the invention may be realized and obtained bymeans of the instrumentalities and combinations particularly pointed outhereinafter.

BRIEF DESCRIPTION OF DRAWINGS

[0018] The accompanying drawings, which are incorporated in andconstitute a part of the specification, illustrate embodiments of theinvention, and together with the general description given above and thedetailed description of the embodiments given below, serve to explainthe principles of the invention.

[0019]FIG. 1A is a cross-sectional view showing a part of a luminescentpanel according to a first embodiment of the present invention, and FIG.1B is a graph showing a luminescent characteristic of this luminescentpanel;

[0020]FIG. 2 is a cross-sectional view showing a part of the luminescentpanel including a switching element;

[0021]FIG. 3A is a cross-sectional view showing a part of a luminescentpanel according to a second embodiment, and FIG. 3B is a graph showing aluminescent characteristic of this luminescent panel;

[0022]FIG. 4A is a cross-sectional view showing a part of a luminescentpanel according to a third embodiment, and FIG. 4B is a graph showing aluminescent characteristic of this luminescent panel;

[0023]FIG. 5A is a cross-sectional view showing a part of a luminescentpanel according to a fourth embodiment, and FIG. 5B is a graph showing aluminescent characteristic of this luminescent panel;

[0024]FIG. 6A is a cross-sectional view showing a part of a luminescentpanel according to a fifth embodiment, and FIG. 6B is a graph showing aluminescent characteristic of this luminescent panel;

[0025]FIG. 7A is a cross-sectional view showing a part of a luminescentpanel according to a sixth embodiment, and FIG. 7B is a graph showing aluminescent characteristic of this luminescent panel;

[0026]FIG. 8A is a cross-sectional view showing a part of a luminescentpanel according to a seventh embodiment, and FIG. 8B is a graph showinga luminescent characteristic of this luminescent panel;

[0027]FIG. 9A is a cross-sectional view showing a part of a luminescentpanel of an eighth embodiment, and FIG. 9B is a graph showing aluminescent characteristic of this luminescent panel;

[0028]FIG. 10A is a cross-sectional view showing a part of a luminescentpanel of a ninth embodiment, and FIG. 10B is a graph showing aluminescent characteristic of this luminescent panel;

[0029]FIG. 11A is a cross-sectional view showing a part of a luminescentpanel according to a tenth embodiment, and FIG. 11B is a graph showing aluminescent characteristic of this luminescent panel;

[0030]FIG. 12A is a cross-sectional view showing a part of a luminescentpanel according to an eleventh embodiment, and FIG. 12B is a graphshowing a luminescent characteristic of this luminescent panel;

[0031]FIG. 13A is a cross-sectional view showing a part of a luminescentpanel according to a twelfth embodiment, and FIG. 13B is a graph showinga luminescent characteristic of this luminescent panel;

[0032]FIG. 14A is a cross-sectional view showing a part of a luminescentpanel according to a thirteenth embodiment, and FIG. 14B is a graphshowing a luminescent characteristic of this luminescent panel;

[0033]FIG. 15 is a cross-sectional view showing a part of a luminescentpanel according to a fourteenth embodiment;

[0034]FIG. 16 is a cross-sectional view showing a part of a luminescentpanel according to a fifteenth embodiment;

[0035]FIG. 17 is a cross-sectional view showing a part of a luminescentpanel according to a sixteenth embodiment;

[0036]FIG. 18 is a cross-sectional view showing a part of a luminescentpanel according to a seventeen embodiment;

[0037]FIG. 19 is a cross-sectional view showing a part of a luminescentpanel according to an eighteen embodiment;

[0038]FIG. 20 is a cross-sectional view showing a part of a luminescentpanel according to a nineteenth embodiment;

[0039]FIG. 21 is a cross-sectional view showing a part of a luminescentpanel according to a twenty embodiment; and

[0040]FIG. 22 is a cross-sectional view showing a part of a luminescentpanel according to a twenty-first embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION

[0041] Concrete modes of the present invention will now be describedhereinafter with reference to the accompanying drawings. However, ascope of the present invention is not restricted to illustratedembodiment. It is to be noted that, in the embodiments, “seen from aplane surface” means “seen from a direction of a substantial normal lineof a light emitting surface 2 b of a transparent substrate 2”.

[0042]FIG. 1A is a cross-sectional view showing a part of a luminescentpanel to which the present invention is applied.

[0043] This luminescent panel 1 has as a basic structure a laminatedstructure in which an anode electrode 3, an organic EL layer 4(luminescent layer in the broad sense) and a cathode electrode 5 aresequentially laminated on one flat surface 2 a of a transparentsubstrate 2 having a substantially tabular shape in the mentioned order.The anode electrode 3 is constituted by many anode electrode sections orstripes which are separated from each other at predetermined intervals,provided to protrude from one surface of the organic EL layer 4 andextend in a row direction. A plurality of positions where each sectionof the anode electrode 3 and the cathode electrode 5 cross each otherwith the organic EL layer 4 therebetween are defined as respectivepixels, and each pixel selectively emits the light in accordance with avoltage or a current applied to the anode electrode 3 and the cathodeelectrode 5.

[0044] The transparent substrate 2 has a refraction factor of 1.3 to1.6, a thickness of 0.1 mm to 1.3 mm, the transmissivity with respect tothe visible light and the insulation property, and it is formed of amaterial such as borosilicate glass, quartz glass or any other glass.

[0045] The film of the anode electrode 3 is formed on one surface 2 a ofthe transparent substrate 2. The anode electrode 3 has the conductivityand the transmissivity with respect to the visible light. Furthermore,as the anode electrode 3, one which can efficiently inject electronholes to the organic EL layer 4 is preferable. The anode electrode 3 isformed of, e.g., an indiumtin-oxide (ITO), a zinc-doped indium oxide(In—Zn—O), an indium oxide (In₂O₃), a tin oxide (SnO₂), a zinc oxide(ZnO) or the like, has a refraction index of approximately 2.0 to 2.2and a thickness of 50 nm to 200 nm.

[0046] The organic EL layer 4 is formed with a thickness of 20 nm to 200nm on the anode electrode 3. The organic EL layer 4 may include variouscharge transport layers. For example, the organic EL layer 4 may have athree-layer structure having an electron hole transport layer, anarrow-sense luminescent layer, and an electron transport layersuperimposed on the anode electrode 3 in the mentioned order, or atwo-layer structure having an electron holes transport layer and aluminescent layer in a narrow sense superimposed on the anode electrode3, or a structure having one layer consisting of a narrow-senseluminescent layer, four or more layers, or a structure having anelectron transport layer or an electron transport layer interposedbetween appropriate layers in such layer structures, or any otherstructure. A refraction factor of the organic EL layer 4 isapproximately 1.3 to 1.6.

[0047] The organic EL layer 4 has a function to transport electron holesand electrons and a function to generate excitons by re-coupling of theelectron holes and the electrons and emit the light. It is desirablethat the organic EL layer 4 is an organic chemical compound which iselectronically neutral, and the electron holes and the electrons arethereby injected and transported in the organic EL layer 4 in thewell-balanced manner. Further, a material having an electron transportproperty may be appropriately mixed in the narrow-source luminescentlayer, a material having an electron hole transport property may beappropriately mixed in the narrow-source luminescent layer, or amaterial having an electron transport property and a material having anelectron transport property may be appropriately mixed in thenarrow-source luminescent layer. A luminescent material (fluorescentmaterial) is included in the organic EL layer 4. This luminescentmaterial may be a high-molecular-based material or a low-molecular-basedmaterial.

[0048] The film of the cathode electrode 5 is formed on the organic ELlayer 4. The cathode electrode 5 has a transmissivity with respect tothe visible light. Furthermore, it is desirable that the cathodeelectrode 5 is formed of a material with a relatively low work functionin light of an electron injection property. As the cathode electrode 5,it is desirable to adopt one which has a laminated structure that thefilm of the electron injection layer constituted by an elementalsubstance with a low work function, e.g., indium, magnesium, calcium,lithium or barium, or an alloy or a mixture including at least one kindof these materials is formed with a thickness of approximately 2 nm to15 nm on the organic EL layer 4 and the film of the high-transmissivitylayer such as ITO is formed with a thickness of 50 nm to 200 nm on theelectron injection layer, and the laminated structure of which transmitstherethrough not more than 70% of the visible light.

[0049] A lens array (fly-eye lens or fly-eye lenses) 7 having aplurality of minute convex lenses aligned therein in the matrix form isbonded to the cathode electrode 5 by an optical adhesive 6. The opticaladhesive 6 has a transmissivity with respect to the visible light, and arefraction factor approximating a refraction factor of thehigh-transmissivity layer of the cathode electrode 5 or a refractionfactor of the lens array 7. In this embodiment, although Canada balsamis used as the optical adhesive 6, the optical adhesive is notrestricted to Canada balsam.

[0050] The lens array 7 has a flat surface 7 a which is bonded to thecathode electrode 5. On the other surface 7 b of the lens array 7 arearranged a plurality of convex lenses 7c in the matrix form with a pitchof 1 μm to 200 μm, or more desirably 25 μm to 75 μm when seen from theplane surface. Each convex lens 7 c has such a shape as that a bottomsurface of a circular cone 7 e is superimposed on an upper surface of atruncated cone 7 d, a ratio of a height 2 x of the truncated cone 7 dand a height x of the circular cone 7 e is 2:1, and a ratio of a radius3 x of the bottom surface of the truncated cone 7 d and a radius 2 x ofthe bottom surface of the circular cone 7 e is 3:2. Therefore, an apexangle α of the circular cone 7 e is set to 120°.

[0051] A reflecting film 8 is formed on an irregular surface orconcave/convex surface 7 b of the lens array 7. The reflecting film 8has a reflectivity with respect to the visible light. As a material ofthe reflecting film 8, there may be used aluminium, silver and an alloyof these materials, but the material of the reflecting film 8 does nothave to be restricted them as long as the irregular surface 7 b of thelens array 7 is a mirror finished surface and can reflect the visiblelight. As a method of forming the reflecting film 8, there are asputtering method, a vapor deposition method and others, it is notnecessary to restrict it to them.

[0052] Since the convex lens 7 c has a concave shape protruding in adirection opposite to a direction toward the transparent substrate 2,one convex lens 7 c and a part of the reflecting film 8 form one concavemirror when viewing the lens array 7 from the transparent substrate 2.This concave mirror faces the cathode electrode 5, and the cathodeelectrode 5 is interposed between the concave mirror and the anodeelectrode 3.

[0053] As a method of manufacturing the luminescent panel 1 having theabove-described structure, the film of the anode electrode 3 is firstformed on the flat surface 2 a of the transparent substrate 2, and thefilm of the organic EL layer 4 is formed on the anode electrode 3. Then,the film of the cathode electrode 5 is formed on the organic EL layer 4.On the other hand, the film of the reflecting film 8 is formed on theirregular surface 7 b of the lens array 7. Then, the optical adhesive 6is applied on at least one of the cathode electrode 5 on the transparentsubstrate 2 side and the flat surface 7 a of the lens array 7, and theoptical adhesive 6 is used to bond the flat surface 7 a of the lensarray 7 to the cathode electrode 5. The optical adhesive 6 is cured,thereby bringing the luminescent panel 1 to completion.

[0054] In case of using the luminescent panel 1 as a display panel of anactive matrix display type display, as shown in FIG. 2, it is goodenough to partition the anode electrode 3 and the organic EL layer 4 inthe matrix form when seen from the plane surface (that is, it is good todefine a plurality of rectangular anode electrode sections and organicEL sections distanced from each other in the line direction and the rowdirection). In this case, the anode electrode sections and the organicEL layer sections are partitioned by an insulative partition wall 9formed in the mesh form or a plurality of walls when seen from the planesurface, the cathode electrode 5 which can function as a commonelectrode is arranged so as to cover the organic EL layers 4 and thepartition wall 9. In the organic EL element which becomes each pixel inthis manner, a luminescent area is partitioned by each section of theanode electrode 3 partitioned by the partition wall 9, and a transistorTr provided in the partition wall 9 is connected as a switching elementto each section of the anode electrode 3. One or more transistors Tr areprovided in accordance with each pixel. An a-Si/TFT or p-Si/TFT ispreferable as the transistor. A capacitor connected to-the transistor Trmay be provided for each pixel according to needs.

[0055] Each convex lens 7 c is arranged in accordance with each pixel(organic EL element), and one concave mirror constituted by one convexlens 7 c and a part of the reflecting film 8 faces each organic EL layer4 of the organic EL element. It is to be noted that the cathodeelectrode 5 of each organic EL element is determined as an electrodecommon to all the pixels, but the electrode connected to the transistorTr may be determined as a cathode electrode whose side close to thetransparent substrate 2 is patterned in accordance with each pixel withrespect to the organic EL layer 4, and the anode electrode may bedetermined as one common electrode so as to cover the partition wall 9and the organic EL layer 4. At this moment, when the cathode electrodeis configured to have an electron injection layer and ahigh-transmissivity layer as described above, providing the electroninjection layer on the organic EL layer 4 side can suffice.

[0056] Moreover, in case of a simple matrix, between a plurality of thepartition walls 9 arranged so as to be separated from each other by apredetermined distance along the line direction when seen from the planesurface may be arranged each anode electrode 3 likewise provided alongthe line direction, and the organic EL layer 4 is formed on the surfaceof the anode electrode 3. Thereafter, a plurality of the cathodeelectrodes 5 separated from each other by a predetermined distance maybe formed on the surface of the organic EL layer 4 along the rowdirection orthogonal to the line direction.

[0057] When a step is generated in the plane direction by the transistorTr and the partition walls 9 or the anode electrode 3 and the organic ELlayer 4, since the optical adhesive 6 having the flexibility whenunhardened is interposed in a gap produced in the irregularities so asto cancel out the irregularities, the lens array 7 can be stably bondedto the transparent substrate 2 in parallel.

[0058] As a method of manufacturing the luminescent panel 1 shown inFIG. 2, a plurality of the anode electrodes 3 are patterned in thematrix form on the flat surface 2 a of the transparent substrate 2 byappropriately performing a thin film formation step such as a vaporevaporation method, a sputtering method or a CVD method, a masking stepsuch as a photolithography method, or the thin film shape manufacturingstep such as an etching method. Then, wirings connecting the transistorsTr and a drive circuit which controls, the transistors Tr and the pixelsare formed between a plurality of the anode electrodes 3 on thetransparent substrate 2.

[0059] Subsequently, each partition wall 9 is formed on the transistorTr and the wiring by the photolithography method. That is, a resist film(photosensitive polyimide film) is formed on the flat surface 2 a of thetransparent substrate 2, the part of the resist film which can be thepartition wall 9 is exposed (that is, the part superimposed on the anodeelectrode 3 is exposed), and a part other than the exposed part of theresist film is eliminated by a developer. As a result, shaping of theresist film is performed so that the remaining part of the resist filmbecomes the partition wall 9.

[0060] Thereafter, a high-molecular material including a luminescentmaterial is solved by a solvent, and the solvent is caused to belch outas droplets to each surrounded area surrounded by the partition wall 9.Then, the droplet spreads on the anode electrode 3 and becomes a film.When this film-is hardened, the organic EL layer 4 is formed.

[0061] Subsequently, the cathode electrode 5 is formed by the filmforming step such as a vapor deposition method, a sputtering method or aCVD method. Although the number of the cathode electrode 5 shown in FIG.2 is one, a plurality of the cathode electrodes 5 arranged in the matrixform may be used in some cases. In such a case, after forming the filmof a conductive film which can be the cathode electrode, a plurality ofcathode electrodes 5 arranged in the matrix shape are formed byperforming the masking step such as a photolithography method or thethin film shape manufacturing step such as an etching method.

[0062] The reflecting film 8 is formed on the irregular surface 7 b ofthe lens array 7. Then, the optical adhesive 6 is applied to at leastone of the cathode electrode 5 on the transparent substrate 2 side andthe flat surface 7 a of the lens array 7, and the optical adhesive 6 isused to bond the flat-surface 7 a of the 2 b lens array 7 to the cathodeelectrode 5. At this moment, positioning is performed in such a mannerthat each convex lens 7 c is superimposed on each cathode electrode 5when seen from the plane surface, and the lens array 7 is bonded to thecathode electrodes 5. Then, the optical adhesive 6 is hardened, therebybringing the luminescent panel 1 shown in FIG. 2 to completion.

[0063] In the luminescent panel 1 shown in FIG. 1A or FIG. 2, when theforward bias voltage (the potential of the anode electrode 3 is higherthan the potential of the cathode electrode 5) is applied between theanode electrode 3 and the cathode electrode 5, the electron holes areinjected into the organic EL layer 4 from the anode electrode 3, and theelectrons are injected from the cathode electrode 5 into the organic ELlayer 4. Then, the electron holes and the electrons are transported tothe narrow-sense luminescent layer of the organic EL layer 4, and theelectron holes and the electrons are re-coupled in the narrow-senseluminescent layer, thereby generating the excitons. The excitons excitethe fluorescent material in the organic EL layer 4 to emit the light.Since the anode electrode 3 and the substrate 2 are transparent withrespect to the luminescent wavelength band of the organic EL layer 4, apart of the light emitted in the organic EL layer 4 passes through theanode 3 and the transparent substrate 2, and outgoes from the flat lightemitting surface 2 b of the transparent substrate 2. Since the cathodeelectrode 5, the optical adhesive 6 and the lens array 7 are alsotransparent with respect to the luminescent wavelength band of theorganic EL layer 4, the remaining part of the light from the organic ELlayer 4 is reflected on the reflecting film 8 through the cathodeelectrode 5, the optical adhesive 6 and the lens array 7, and thereflected light passes through the lens array 7, the transparentadhesive 6, the cathode electrode 5, the organic EL layer 4, the anodeelectrode 3 and the transparent substrate 2, and outgoes from the lightemitting surface 2 b.

[0064] In the luminescent panel 1 shown in FIG. 1A or FIG. 2, since theconcave mirror faces the cathode electrode 5, the light directed towardthe reflecting film 8 from the organic EL layer 4 is reflected so as tobe condensed at the central part. That is, the light directed toward thereflecting film 8 from the organic EL layer 4 passes the apex of theconvex lens 7 c and is reflected so as to be condensed or focused towardthe normal line direction of the light emitting surface 2 b. Therefore,the luminescent brightness of the luminescent panel 1 is very high whenseen from the normal line direction of the light emitting surface 2 b.Therefore, the light emitted from the organic EL layer 4 can beprevented from evenly spreading in the radial pattern on the lightemitting surface 2 b. In particular, when it is used for the matrixdisplay type display like the luminescent panel 1 shown in FIG. 2, sincethe light emitted from the organic EL layer 4 can be suppressed fromspreading in the radial pattern, it is not strongly diffused tosurrounding pixels, and display with the high contrast ratio can berealized.

[0065] A graph of FIG. 1B is a graph showing the directivity of theoutgoing light of the luminescent panel 1 shown in FIG. 1A, in whichangles of axes radially extending from a starting point O in the lightemitting surface 2 b represent measured angles with respect to the lightemitting surface 2 b, and distances from the starting point O representlight intensity ratios (ratios of the brightness [cd/m²]). Thetransparent substrate 2 is set to have a refraction factor of 1.5 and athickness of 0.7 mm. It is to be noted that the anode electrode 3, theorganic EL layer 4, the cathode electrode 5 and the optical adhesive 6are very thin as compared with the transparent substrate 2. Asrefraction factors of these members, it is desirable to adopt refractionfactors which do not greatly affect the directivity of the lightintensity ratio but are low.

[0066] A line L901 represents a light intensity ratio of the luminescentpanel 901 of FIG. 22 (where the cathode electrode 905 has thereflectivity with respect to the visible light). Providing that thelight intensity ratio is 1 when seen from the normal line direction, thelight intensity ratio of any angle is dimensionless.

[0067] A line L1 represents a light intensity ratio of the luminescentpanel 1 of FIG. 1A, and this is a relative value expressing the lightintensity as 1 when viewing the luminescent panel 901 from the normalline direction of the surface 902 b as a comparative example.

[0068] Various conditions in this embodiment (e.g., a film thickness ofeach layer, a material of each layer, a level of an application voltage,a luminescent area, a level of a passing current and others) are equalto those in the prior art except that the lens array 7 and thereflecting film 8 are provided.

[0069] As shown in FIG. 1B, the brightness in the luminescent panel 1according to this embodiment is substantially the same as the brightnessin the prior art luminescent panel in the angle range of 0° to 60°.However, in case of an angle more than 60°, the brightness in theluminescent panel 1 in this embodiment is higher than the brightness inthe prior art luminescent panel. In particular, when the angle is notless than 80°, a difference in brightness is considerable.

[0070] As described above, since the luminescent panel 1 includes theconcave mirror so as to be opposed to the transparent cathode electrode5, the emitting efficiency is improved within 30° on the right and leftsides with respect to the light emitting surface 2 b. In particular, theemitting efficiency within 5° on the right and left sides is improved tobe double or more.

[0071] In addition, since the concave mirror is provided so as to beopposed to the transparent cathode electrode 5, the brightness when seenfrom the normal line direction with respect to the light emittingsurface 2 b becomes high without increasing the current or the voltageof the luminescent panel 1. In other words, since the luminescentbrightness becomes high without increasing the level of the currentflowing through the luminescent panel 1, the long duration of life andthe low power consumption of the luminescent panel 1 can be realized,thereby improving the light emitting efficiency of the luminescent panel1.

[0072] When this luminescent panel 1 is used as the display panel of thedisplay, the brightness when seen from the normal line directionrelative to the light emitting surface 2 b is high, thereby providingthe display with the high contrast.

[0073] By appropriately changing the shape of the lens array, the shapeof the concave mirror can be appropriately varied as shown in FIGS. 3A,4A, 5A, 6A, 7A and 8A. In the luminescent panels 10 to 15 shown in FIGS.3A, 4A, 5A, 6A, 7A and 8A described below, like reference numeralsdenote constituent elements equal to those in the luminescent panel 1.In these embodiments, the anode electrodes 3 are separated from eachother in the row direction by a plurality of protrusions which areprovided on one surface of the organic EL layer 4 so as to protrude atpredetermined intervals in the row direction and extend in the columndirection, and the cathode electrodes 5 are separated from each other inthe line direction by a plurality of protrusions (not shown in thedrawing) which are provided on the other surface so as to protrude withpredetermined intervals in the column direction and extend in the rowdirection. In this manner, the separated anode electrode sections orfirst strip electrodes cross the separated cathode electrode sections orsecond strip electrodes at many points, and these parts and the parts ofthe organic EL layer sandwiched therebetween constitute pixels.

[0074] In the luminescent panel 10 shown in FIG. 3A, as to the shape ofthe lens array 71, its surface 71 a bonded to the cathode electrode 5 isa flat surface. Irregular surface 71 b on the opposite side has a shapethat a plurality of convex lenses 71 c are arranged in the matrix shapewhen seen from the plane surface. The convex lens 71 c has asubstantially circular cone shape. Forming the film of a reflecting film8 on the irregular surface 71 b forms concave mirrors consisting of theconvex lenses 71 c and the reflecting film 8. Additionally, two oppositeside lines which are in contact with an apex angle α are set to the samelength. In FIG. 3B, a line L10 represents a light intensity ratio of theluminescent panel 10 shown in FIG. 3A, and this is expressed as arelative value representing the light intensity as 1 when viewing theluminescent panel 901 from the normal line direction of the surface 902b. Here, there are illustrated cases where the apex angles α of theconvex lens 71 c are 90° and 100°. In any case, this panel is brighterover 180° than the luminescent panel 901. In particular,.the brightnesswhen seen from the normal line direction relative to the light emittingsurface 2 b is greatly high as compared with the prior art, and thistendency is more prominent when the apex angle α is 100° rather than90°.

[0075] In the luminescent panel 11 shown in FIG. 4A, as to the shape ofthe lens array 72, its surface 72 a bonded to the cathode electrode 5 isa flat surface. An irregular surface 72 b on the opposite side has ashape that a plurality of convex lenses 72 c are arranged in the matrixshape when seen from the plane surface. The convex lens 72 c has atruncated cone shape, and a ratio of a height x from a valley of thetruncated cone to a small upper surface and a diameter x of the smallupper surface is 1:1 whilst a ratio of a diameter 3 x of a large bottomsurface of the truncated cone (distance between valleys) and a width xof the small upper surface is 3:1. The reflecting film 8 is formed onthe irregular surface 72 b, so that concave mirrors consisting of theconvex lenses 72 c and the reflecting film 8 are formed. In FIG. 4B, aline L11 represents a light intensity ratio of the luminescent panel 11of FIG. 4A, and this is expressed as a relative value representing thelight intensity as 1 when viewing the luminescent panel 901 from thenormal line direction of the surface 902 b as a comparative example. Theluminescent panel 11 is brighter over approximately 180° than theluminescent panel 901. In particular, it demonstrates the brightnessequal to or above the front face brightness of he luminescent panel 901over approximately 40° on the right and left sides relative to thenormal line direction of the light emitting surface 2 b.

[0076] In the luminescent panel 12 shown in FIG. 5A, as to the shape ofthe lens array 73, its surface 73 a bonded to the cathode electrode 5 isa flat surface. Its irregular surface 73 b on the opposite side has ashape that a plurality of convex lenses 73 c are arranged in the matrixfrom when seen from the plane surface. The convex lens 73 c has atruncated cone shape, and a ratio of a height x of the truncated coneand a diameter 4 x of a small upper surface is 1:4 whilst a ratio of adiameter 6 x of a large bottom surface of the truncated cone and a width4 x of the small upper surface is 6:4. Forming the reflecting film 8 onthe irregular surface 73 b constitutes a concave mirrors consisting ofthe convex lenses 73 c and the reflecting film 8. In FIG. 5B, a line L12represents a light intensity ratio of the luminescent panel 12 shown inFIG. 5A, and this is expressed as a relative value representing thelight intensity as 1 when viewing the luminescent panel 901 from thenormal line direction of the surface 902 b as a comparative example. Theluminescent panel 12 is brighter over approximately 180° than theluminescent panel 901. In particular, it demonstrates the brightnessequal to or above the front face brightness of the luminescent panel 901over approximately 40° on the right and left sides with respect to thenormal line direction of the light emitting surface 2 b.

[0077] In the luminescent panel 13 shown in FIG. 6A, as to the shape ofthe lens array 74, its surface 74 a bonded to the cathode electrode 5 isa flat surface. Its irregular surface 74 b on the opposite side has ashape that a plurality of convex lenses 74 c are arranged in the matrixform when seen from the flat surface. The convex lens 74 c has a curvedsurface and a semispherical shape that a height of the convex portion isx with respect to a distance 2 x between concave portions of the convexlens 74 c. The reflecting film 8 is formed on the irregular surface 74b, so that concave mirrors consisting of the convex lenses 74 c and thereflecting film 8 are formed. In FIG. 6B, a line L13 represents a lightintensity of the luminescent panel 13 shown in FIG. 6A, and this isexpressed as a relative value representing the light intensity as 1 whenviewing the luminescent panel 901 from the normal line direction of thesurface 902 b. The luminescent panel 13 is brighter than the luminescentpanel 901 over approximately 40° on the right and left sides of thenormal line direction of the light emitting surface 2 b.

[0078] In the luminescent panel 14 shown in FIG. 7A, as to the shape ofthe lens array 75, its surface 75 a bonded to the cathode electrode 5 isa flat surface. Its irregular surface 75 b on the opposite side has ashape that a plurality of convex lenses 75 c are arranged in the matrixform when seen from the plane surface. A cross-sectional shape of theconvex lens 75 c is semioval, and a ratio of the major axis 3 x (widthof the bottom surface) and the minor axis 2 x (height) is 3:2. Thereflecting film 8 is formed on the irregular surface 75 b, so that anon-spherical concave mirrors consisting of the convex lenses 75 c andthe reflecting film 8 are formed. In FIG. 7B, a line L14 represents alight intensity ratio of the luminescent panel 14 shown in FIG. 7A, andthis is expressed as a relative value representing the light intensityas 1 when viewing the luminescent panel 901 from the normal linedirection of the surface 902 b as a comparative example. The luminescentpanel 14 is brighter than the luminescent panel 901 over approximately60° on the right and left sides with respect to the normal linedirection of the light emitting surface 2 b.

[0079] In the luminescent panel 15 of FIG. 8A, as to the shape of a lensarray 76, its surface 76 a bonded to the cathode electrode 5 is a flatsurface. Its irregular surface 76 b on the opposite side has a shapethat a plurality of convex lenses 76 c are arranged in the matrix formwhen seen from the plane surface. A cross-sectional shape of the convexlens 76 c is semioval, and a ratio of the minor axis (width of thebottom surface) and the major axis (height) is 2:3. The reflecting film8 is formed on the irregular surface 76 b, so that non-spherical concavemirrors consisting of the convex lenses 76 c and the reflecting film 8are formed. In FIG. 8B, a line L15 represents a light intensity of theluminescent panel 15 shown in FIG. 8A, and this is expressed as arelative value representing the light intensity as 1 when viewing theluminescent panel 901 from the normal line direction of the surface 902b as a comparative example. The luminescent panel 15 is brighter thanthe luminescent panel 901 over approximately 20° to 35° on the right andleft sides with respect to the normal line direction of the lightemitting surface 2 b.

[0080] In FIGS. 3A, 4A, 5A, 6A, 7A and 8A, the anode electrode 3, theorganic EL layer 4 and the cathode electrode 5 may be partitioned bypartition walls 9 in the matrix form seen from the plane surface asshown in FIG. 2. In this case, one concave mirror constituted by one ofthe convex lenses 71 c to 76 c and the part of the reflecting film 8faces one partitioned area (the anode electrode 3, the organic EL layer4 and the cathode electrode 5 are superimposed in this area).

[0081] In the luminescent panels 1, 10 to 12 shown in FIGS. 1A, 2, 3A,4A and 5A, a translucent lens array may be provided on one surface ofthe transparent substrate 2.

[0082]FIG. 9A shows a luminescent panel 1′ in which the transparentsubstrate 2 of the luminescent panel 1 shown in FIG. 1A is substitutedby a transparent lens array substrate 21. The anode electrode 3, theorganic EL layer 4 and the cathode electrode 5 are sequentiallysuperimposed on the flat surface 21 a of the lens array substrate 21. Acorrugated surface 21 b of the lens array substrate 21 is a lightemitting surface, and a plurality of convex lenses 21 c are arranged inthe matrix form. The convex lens 21 c has a circular cone shape that twoopposite side lines which are in contact with an apex angle β in a crosssection along an apex have the same length y. When seen from the planesurface, each convex lens 21 c is superimposed on the convex lens 7 c insuch a manner that an apex of each convex lens 21 c is opposed to theapex of the convex lens 7 c. In FIG. 9B, a light L1′ represents a lightintensity ratio of the luminescent panel 1′ in FIG. 9A, and this isexpressed as a relative value representing the light intensity as 1 whenviewing the luminescent panel 901 from the normal line direction of thesurface 902 b as a comparative example. The luminescent panel 1′ isbrighter than the luminescent panel 901 over approximately 180°. Inparticular, it demonstrates the brightness equal to or above the frontface brightness of the luminescent panel 901 over approximately 60° onthe right and left sides from the front face direction of the lens-arraysubstrate 21.

[0083]FIG. 10A shows a luminescent panel 10′ in which the transparentsubstrate 2 of the luminescent panel 10 shown in FIG. 3A is substitutedby a lens array substrate 21. The anode electrode 3, the organic ELlayer 4 and the cathode electrode 5 are sequentially laminated on theflat surface 21 a of the lens array substrate 21. The corrugated surface21 b of the lens array substrate 21 is a light emitting surface, and aplurality of convex lenses 21 c are arranged in the matrix form. Theconvex lens 21 c has the same circular cone shape as that shown in FIG.9A. Further, each convex lens 21 c is superimposed on the convex lens 71c in such a manner that the apex of each convex lens 21 c is opposed tothe apex of the convex lens 71 c when seen from the plane surface. InFIG. 10B, a line L10′ represents a light intensity ratio of theluminescent panel 10′ shown in FIG. 10A, and this is expressed as arelative value representing the light intensity as 1 when viewing theluminescent panel 901 from the normal line direction of the surface 902b as a comparative example. Here, there are illustrated a case that anapex angle β of the convex lens 21 c and an apex angle α of the convexlens 71 c are 900 and a case that the apex angle β of the convex lens 21c and the apex angle α of the convex lens 71 c are 1000. The luminescentpanel 10′ is brighter than the luminescent panel 901 over approximately180° even if the both apex angles α and β are 90° or 100°. Inparticular, it demonstrates the brightness equal to or above the frontface brightness of the luminescent panel 901 over approximately 40° onthe right and left sides from the front face direction of the lens arraysubstrate 21.

[0084]FIG. 11A illustrates a luminescent panel 11′ in which thetransparent substrate 2 of the luminescent panel 11 shown in FIG. 4A issubstituted by the lens array substrate 21. The anode electrode 3, theorganic EL layer 4 and the cathode electrode 5 are sequentiallylaminated on the flat surface 21 a of the lens array substrate 21. Thecorrugated surface 21 b of the lens array substrate 21 is a lightemitting surface, and a plurality of convex lenses 21 c are arranged inthe matrix form. The convex lens 21 c has the same circular cone shapeas that shown in FIG. 9A. Furthermore, each convex lens 21 c issuperimposed on the convex lens 72 c in such a manner that the apex ofeach convex lens 21 c is opposed to the small bottom surface of thetruncated cone of the convex lens 72 c when seen from the plane surface.In FIG. 11B, a line L11′ represents a light intensity ratio of theluminescent panel 11′ illustrated in FIG. 11A, and this is expressed asa relative value representing the light intensity as 1 when viewing theluminescent panel 901 from the normal line direction of the surface 902b as a comparative example. Here, there is illustrated a case that theapex angle β of the convex lens 21 c is 100°. The luminescent panel 11′is brighter than the luminescent panel 901 over approximately 180°. Inparticular, it demonstrates the brightness equal to or above the frontface brightness of the luminescent panel 901 over approximately 45° onthe right and left sides from the front face direction of the lens arraysubstrate 21.

[0085]FIG. 12A shows a luminescent panel 12′ in which the transparentsubstrate 2 of the luminescent panel 12 depicted in FIG. 5A issubstituted by a lens array substrate 21. The anode electrode 3, theorganic EL layer 4 and the cathode electrode 5 are sequentiallylaminated on the flat surface 21 a of the lens array substrate 21. Onthe other hand, the corrugated surface 21 b of the lens array substrate21 is a light emitting surface, and a plurality of convex lenses 21 care arranged in the matrix form. The convex lens 21 c has a circularcone shape. Moreover, each convex lens 21 c is superimposed on theconvex lens 73 c in such a manner that the apex of each convex lens 21 cis opposed to a small bottom surface of the truncated cone of the convexlens 73 c when seen from the plane surface. In FIG. 12B, a line L12′represents a light intensity ratio of the luminescent panel 12′ shown inFIG. 12A, and this is expressed as a relative value representing thelight intensity as 1 when viewing the luminescent panel 901 from thenormal line direction of the surface 902 b. Here, there is illustrated acase that the apex angle β of the convex lens 21 c is 100°. Theluminescent panel 12′ is brighter than the luminescent panel 901 overapproximately 180°. In particular, it demonstrates the brightness equalto or above the front face brightness of the luminescent panel 901 overapproximately 45° on the right and left sides from the front facedirection of the lens array substrate 21.

[0086]FIG. 13A shows a luminescent panel 10″ in which the transparentsubstrate 2 of the luminescent panel 10 depicted in FIG. 3A issubstituted by the lens array 22. The anode electrode 3, the organic ELlayer 4 and the cathode electrode 5 are sequentially superimposed on theflat surface 22 a of the lens array 22. The corrugated surface 22 b ofthe lens array 22 is a light emitting surface, and a plurality of convexlenses 22 c arranged in the matrix form are formed by the corrugatedsurface 22 b. The convex lens 22 c has a circular cone shape. Inaddition, the convex lens 22 c is shifted from the convex lens 71 c by ahalf pitch in column and row directions. That is, the apex of eachconvex lens 22 c is opposed to a valley between the convex lenses 71 cand each valley between the convex lenses 22 c is opposed to the apex ofthe convex lens 71 c when seen from the plane surface. In FIG. 13B, aline L10″ represents a light intensity ratio of the luminescent panel10″ depicted in FIG. 13A, and this is expressed as a relative valuerepresenting the light intensity as 1 when viewing the luminescent panel901 from the normal line direction of the surface 902 b. Here, there areillustrated a case that the apex angle β of the convex lens 22 c and theapex angle α of the convex lens 71 c are 90° and a case that the apexangle β of the convex lens 21 c and the apex angle α of the convex lens71 c are 100°. The luminescent panel 10″ is brighter than theluminescent panel 901 over approximately 180° even if the both apexangles α and β are 90° or 100°. In particular, it demonstrates thebrightness equal to or above the front face brightness of theluminescent panel 901 over approximately 45° on the right and left sidesfrom the front face direction of the lens array 22.

[0087] Although the lens array may not be bonded to the cathodeelectrode 5, the lens array must be used rather than the transparentsubstrate in this case. FIG. 14A shows an example of such a luminescentpanel 16.

[0088] As shown in FIG. 14A, the anode electrode 3, the organic EL layer4 and the cathode electrode 51 are sequentially superimposed on the flatsurface 21 a of the lens array substrate 21. This cathode electrode 51is different from the cathode electrode 5 in that it does not have thetransmissivity with respect to the visible light but has thereflectivity. Therefore, the cathode electrode 5 acts with the mirrorsurface. On the other hand, the corrugated surface 21 b of the lensarray substrate 21 is a light emitting surface, and the convex lenses 21c are arranged in the matrix form. The convex lens 21 c has a circularcone shape. In FIG. 14B, a line L16 represents a light intensity ratioof the luminescent panel 16 of FIG. 14A, and this is expressed as arelative value representing the light intensity as 1 when viewing theluminescent panel 901 from the normal line direction of the surface 902b as a comparative example. Here, there are illustrated cases that theapex angle β of the convex lens 21 c is 90° and 100°, respectively. Theluminescent panel 12′ is brighter than the luminescent panel 901 overapproximately 180° even if the apex angle β is either 90° or 100°. Inparticular, it demonstrates the brightness equal to or above the frontface brightness of the luminescent panel 901 over approximately 30° onthe right and left sides from the front face direction of the lens arraysubstrate 21.

[0089] Although the concave mirror is formed by bonding the flat surfaceof the lens array having the reflecting film formed thereon to thecathode electrode in the foregoing embodiments, the present invention isnot restricted to the above embodiments as long as the concave mirrorfaces the cathode electrode.

[0090] For example, in the luminescent panel 17 shown in FIG. 15, thereflecting film 8 is formed in such a manner that its outer surface(outer surface relative to the organic EL layer 4) is in contact withthe irregular surface 32 a of the opposed substrate 32. That is, sincethe shape of the reflecting film 8 can be formed in accordance with theshape of the irregular surface 32 a of the opposed substrate 32, thedirectivity of the reflected light on the reflecting film 8 can be setby setting the shape of the irregular surface 32 a of the opposedsubstrate 32. Additionally, spaces 31 are formed between the cathodeelectrode 5 and the reflecting film 8, an inert gas with a rowrefraction factor (e.g., a nitrogen gas, a helium gas, an argon gas, aneon gas and others) is filled in the spaces 31, thereby restrictingcorrosion of the cathode electrode 5 and the reflecting film 8.

[0091] As a method of manufacturing the luminescent panel 17, afterforming the film of the anode electrode 3 on the flat surface 2 a of thetransparent substrate 2, the transistor or the partition wall (notshown) is formed according to needs, and the anode electrode 3, theorganic EL layer 4 and the cathode electrode 5 are sequentially formed.Then, a concave portion 32 c is formed on one surface of the opposedsubstrate 32 (the concave portion 32 c is not formed at this moment) bythe photolithography step.

[0092] The reflecting film 8 is formed on the irregular surface 32 a ofthe opposed substrate 32 by the vapor deposition method or the like, thetransparent substrate 2 and the opposed substrate 32 are attached toeach other in such a manner that the reflecting film 8 is arranged onthe cathode electrode 5 side, thereby bringing the luminescent panel 17to completion. On the irregular surface 32 a, a plurality of the concaveportions 32 c are patterned in the mesh formed as seen from the planesurface, and the spaces 31 are arranged in the matrix form as seen fromthe plane surface. It is to be noted that a silhouette of the space 31has the same shape as a silhouette of the convex lens 7 c shown inFIG. 1. It is desirable that the reflecting film 8 is in contact withthe cathode electrode 5 in terms of the reflectivity or the contrastratio. However, when a plurality of stripe electrodes constituting thecathode electrode 5 are provided and signals applied to the respectivecathode electrode stripes are different from each other, it is desirableto interpose an insulating material so that the reflecting film 8 andthe cathode electrode stripes are electrically insulated from eachother. When the step of attaching the transparent substrate 2 and theopposed substrate 32 with each other is performed in the inert gasatmosphere, the space 31 has the inert gas atmosphere therein. Attachingthe opposed substrate 32 having the reflecting film 8 formed thereon tothe transparent substrate 2 forms concave mirrors facing the cathodeelectrode 5.

[0093] In regard to the luminescent panel 17, like reference numeralsdenote constituent elements equal to those in the luminescent panel 1.

[0094] The reflecting film 8 of the luminescent panel 17 may alsofunction as the cathode electrode. In this case, the film of the cathodeelectrode 5 does not have to be formed on the organic EL layer 4. FIG.16 shows a luminescent panel as such an example. As to the luminescentpanel 18, like reference numerals denote constituent elements equal tothose in the luminescent panel 17. In the luminescent panel 18 shown inFIG. 16, the reflecting film 52 which reflects the visible light isformed on the irregular surface 32 a of the opposed substrate 32, thespaces 31 is formed between the organic EL layer 4 and the reflectingfilm 52. The space 31 has the inert gas atmosphere (e.g., a nitrogengas, a helium gas, an argon gas, a neon gas and others) therein. Thereflecting film 52 serves as concave mirrors in the spaces 31. Further,the reflecting film 52 is in contact with the organic EL layer 4 at theparts of the concave portion 32 c of the opposed substrate 32 and alsofunctions as the cathode electrode. That is, the surface of thereflecting film 52 which is in contact with the organic EL layer 4 isformed of a material with a relatively low work function.

[0095] As a method of manufacturing the luminescent panel 18, afterforming the film of the anode electrode 3 on the flat surface 2 a of thetransparent substrate 2, the transistor Tr or the partition wall 9 (notshown in FIG. 16) is formed according to needs, and the film of theorganic EL layer 4 is formed on the surface of the anode electrode 3.

[0096] On the other hand, the concave portions 32 c are formed on onesurface of the opposed substrate 32 by the photolithography step.

[0097] Then, the above-described cathode electrode material isevaporated on the irregular surface 32 a of the opposed substrate 32 inorder to form the reflecting film 52, and this opposed substrate 3 isattached to the transparent substrate 2 so that the reflecting film 52comes into contact with the organic EL layer 4 to form the spaces 31,thereby bringing the luminescent panel 18 to completion. When this stepis carried out in the inert gas atmosphere, the spaces 31 has the inertgas atmosphere therein.

[0098] The space 31 of the luminescent panel 18 may be filled with theorganic EL layer 4. FIG. 17 shows a luminescent panel 19 as such anexample. As to the luminescent panel 19, like reference numerals denoteconstituent elements equal to those in the luminescent panel 18. In theluminescent panel 19 shown in FIG. 17, the reflecting film 52 is formedon the irregular surface 32 a of the opposed substrate 32, and theorganic EL layer 4 is formed between the anode electrode 3 and thereflecting film 52. Therefore, the reflecting film 52 has the concaveshape with respect to the organic EL layer 4 and functions as concavemirrors. The organic EL layer 4 has a shape that the concave portions 33corresponding to the concave portions 32 c are continuous, and functionas lenses with respect to the light transmitted through the organic ELlayer 4. Additionally, the reflecting film 52 also serves as the cathodeelectrode, and has a laminated structure consisting of a first layerwhich is in contact with the organic EL layer 4 and has a relatively lowwork function and a second layer which is thicker than the first layerand has a relatively high work function. Further, the reflecting film 52has the reflectivity with respect to the visible light.

[0099] The opposed substrate 32 of the luminescent panel 19 may not beprovided. FIG. 18 shows a luminescent panel 20 of such an example. As tothe luminescent panel 20, like reference numerals denote constituentelements equal to those in the luminescent panel 19.

[0100] As a method of manufacturing the luminescent panel 20, afterforming the anode electrode 3 on the flat surface 2 a of the transparentsubstrate 2, the film of the organic EL layer 4 is formed on the anodeelectrode 3. Then, embossing the organic EL layer 4 provides a shapethat the concave portions 4 a of the organic EL layer 4 are arranged inthe matrix form when seen from the plane surface. Further, forming thereflecting film 52 on the organic EL layer 4, the reflecting film 52functions as concave mirrors with respect to the organic EL layer 4.

[0101] In a luminescent panel 30 shown in FIG. 19, a transparent resinwhich transmits the visible light therethrough is filled in the space 31in the luminescent panel 17 depicted in FIG. 15. Although a method ofmanufacturing the luminescent panel 30 is substantially equal to themethod of manufacturing the luminescent panel 17, there is required astep of filling the transparent resin in the space 31 of the irregularsurface 32 a after forming the reflecting film 8 on the irregularsurface 32 a of the opposed substrate 32. Thereafter, when the irregularsurface 32 a having the transparent resin 34 filled therein is bonded tothe cathode electrode 5, the luminescent panel 30 is brought tocompletion. It is desirable for the transparent resin 34 to have arefraction factor substantially equal to that of the cathode electrode 5and also have a low transmissivity with respect to oxygen or water.

[0102] In a luminescent panel 19′ shown in FIG. 20, the transparentsubstrate 2 of the luminescent panel 19 illustrated in FIG. 17 issubstantially substituted by a lens array 102, and a surface 102 a onwhich the organic EL elements are to be formed is an irregular surfaceon which convex lenses 102 c are arranged in the matrix form whilst asurface 102 b on the back side is flat. After patterning the anodeelectrode 3′ on the surface 102 a, the organic EL layer 4′ and thecathode electrode 52 which also functions as the reflecting film areappropriately formed. At this moment, the anode electrode 3′, theorganic EL layer 4′ and the cathode electrode 52 are formed along theconvex shapes of the convex lenses 102 c. A resin is applied to thesurface of the cathode electrode 52 by spin coating, thereby forming theopposed substrate 132 which also functions as a sealing film.

[0103] In order to improve the luminescent brightness of the luminescentpanel, the following structure may be adopted.

[0104] As shown in FIG. 21, a luminescent panel 40 has as a basicstructure a laminated structure that a low-refraction factor materiallayer 43, the anode electrode 44, the organic EL layer 45 and thecathode electrode 46 are sequentially laminated on one flat surface 42 aof the substantially tabular transparent substrate 42.

[0105] The transparent substrate 42 has a transmissivity with respect tothe invisible light and an insulating property, and is formed of amaterial such as a borosilicate glass, a quartz glass or any otherglass. A refraction factor of the transparent substrate 42 isapproximately 1.5.

[0106] The film of the low-refraction factor material layer 43 is formedon one flat surface 42 a of the transparent substrate 42. Thelow-refraction factor material layer 43 has a transmissivity withrespect to the visible light, and a refraction factor of thelow-refraction factor material layer 43 is smaller than that of thetransparent substrate 42. Further, a film thickness of thelow-refraction factor material layer 43 is sufficiently longer than awavelength of the visible light. As the low-refraction factor materiallayer 43, a fluorocarbon resin is appropriate. There are, e.g., PTFE(refraction factor: 1.35), PFA (refraction factor: 1.35), PFEP(refraction factor: 1.34), MEXFLON-H15 (refraction factor: 1.35,manufactured by Nippon Mektron, Ltd.), CYTOP (refraction factor: 1.34,manufactured by Asahi Glass Company) and others.

[0107] The film of the anode electrode 44 is formed on thelow-refraction factor material layer 43. The anode electrode 44 has anelectroconductivity and a transmissivity with respect to the visiblelight. Furthermore, as the anode electrode 44, one which can efficientlyinject the electron holes into the organic EL layer 45 is preferable.The anode electrode 44 is formed of, e.g., an indium-tin-oxide (ITO), azinc-doped indium oxide (IZO), an indium oxide (In₂O₃), a tin oxide(SnO₂) or a zinc oxide (ZnO) and others. It is to be noted that, if theanode electrode 44 is formed of ITO, its refraction factor isapproximately 2.0, which is higher than a refraction factor of thelow-refraction factor material layer 43 and also higher than arefraction factor of the transparent substrate 42.

[0108] The film of the organic EL layer 45 is formed on the anodeelectrode 44. The organic EL layer 45 may have a three-layer structureconsisting of an electron hole transport layer, a narrow-senseluminescent layer and an electron transport layer superimposed on theanode layer 44 in the mentioned order, or a two-layer structureconsisting of the electron hole transport layer and the narrow-senseluminescent layer superimposed on the anode electrode 3, or a singlelayer structure consisting of the narrow-sense luminescent layer, or alaminated structure that an injection layer for electrons or electronholes is interposed between appropriate layers in such layer structures,or any other layer structure.

[0109] That is, the organic EL layer 45 has a function to injectelectron holes and electrons, a function to transport electron holes andelectrons, and a function to generate excitons by re-combining ofelectron holes and electrons to emit the light. Although the organic ELlayer 45 contains a luminescent material (fluorescent material), theluminescent material may be based on a high-molecular material or alow-molecular material.

[0110] The film of the cathode electrode 46 is formed on the organic ELlayer 45. The cathode electrode 46 has a reflectivity with respect tothe visible light. Furthermore, it is desirable for the cathodeelectrode 46 to have a relatively low work function.

[0111] As a method of manufacturing the luminescent panel 40, afluorocarbon resin is applied on one flat surface 42 a of thetransparent substrate 42 and incineration is performed, thereby forminga low-refraction factor material layer 43 having a film thickness ofapproximately 100 μm. Thereafter, the film of the anode electrode 44 isformed on the low-refraction factor material layer 43 at approximately150° C. by a plasma ion plating method, and the film of the organic ELlayer 45 is formed on the anode electrode 44. Then, the cathodeelectrode 46 is formed on the organic EL layer 45 by the vapordeposition method.

[0112] Comparing the luminescent panel 40 with a luminescent panelwithout the low-refraction factor material layer 43, when variousconditions (e.g., a film thickness of each layer, a level of anapplication voltage, a luminescent area, a level of a passing currentand others) are equal, the luminescent brightness of the luminescentpanel 40 is approximately 1.5-fold of the luminescent brightness of theluminescent panel without the low-refraction factor material layer 43.That is because the light is refracted when entering transparentsubstrate 42 from the low-refraction factor material layer 43 by formingthe film of the low-refraction factor material layer 43, a quantity ofthe light which has approximated 90° with respect to the light emittingsurface 42 b is increased, and a quantity of the light totally reflectedon the light emitting surface 42 b is thereby decreased.

[0113] The low-refraction factor material layer 43 may be a materialincluding air gaps (e.g., silica aerogel: 90% of its cubic content isair gaps), or an ultraviolet curing resin material including air gaps.The material including the air gap or the resin has a substantialrefraction factor lower than a refraction factor of a bulk material, andalso lower than a refraction factor of the transparent substrate 42.

[0114] The present invention is not restricted to the foregoingembodiments, and various improvements and changes in design may becarried out without departing from the scope of the invention.

[0115] For example, although there is provided a structure that theanode electrode, the organic EL layer and the cathode electrode aresequentially superimposed from the transparent substrate 2, thetransparent substrate 42, the lens array substrate 21 or the lens array22, there may be adopted a laminated structure that the cathodeelectrode (which has the transmissivity with respect to the visiblelight), the organic EL layer, and the anode electrode (which has thetransmissivity with respect to the visible light when it does notfunction as the reflecting film, and does not have the transmissivitywith respect to the visible light but the reflectivity when it alsofunctions as the reflecting film) are superimposed in the illustratedorder from the transparent substrate 2, the transparent substrate 42,the lens array substrate 21 or the lens array 22.

[0116] Moreover, although description has been given as to the case thatorganic EL element that the anode electrode, the organic EL layer andthe cathode electrode are superimposed in the mentioned order from thetransparent substrate 2, the transparent substrate 42, the lens arraysubstrate 21 or the lens array 22 is applied to the luminescent panel,it is possible to apply to the luminescent panel an inorganic EL elementthat a first electrode (which has the transmissivity with respect to thevisible light), an insulating film (which has the transmissivity withrespect to the visible light), an inorganic luminescent layer, aninsulating film (which has the transmissivity with respect to thevisible light) and a second electrode (which has the transmissivity withrespect to the visible light when it does not function as the reflectingfilm, and does not have the transmissivity with respect to the visiblelight but the reflectivity when it also functions as the reflectingfilm) are superimposed in the mentioned order from the transparentsubstrate 2, the transparent substrate 42, the lens array substrate 21or the lens array 22.

[0117] Additional advantages and modifications will readily occur tothose skilled in the art. Therefore, the invention in its broaderaspects is not limited to the specific details and representativeembodiments shown and described herein. Accordingly, variousmodifications may be made without departing from the spirit or scope ofthe general inventive concept as defined by the appended claims andtheir equivalents.

1. A luminescent panel comprising: a transparent substrate; a firsttransparent electrode provided on the transparent substrate; aluminescent layer provided on the first transparent electrode; a secondtransparent electrode provided on the luminescent layer, the firsttransparent electrode, the luminescent layer and the second transparentelectrode defining at least one pixel; and a reflecting film whichreflects light emitted from the luminescent layer through the secondtransparent electrode and causes the reflected light to is outwardlyemit from the transparent substrate.
 2. The luminescent panel accordingto claim 1, wherein the reflecting film controls a direction of thereflected light.
 3. The luminescent panel according to claim 1, whereinthe reflecting film reflects the light emitted from the luminescentlayer so as to increase the light emitted in a front face direction ofthe transparent substrate.
 4. The luminescent panel according to claim1, further comprising a lens which corresponds to the pixel and isprovided on an inner surface of the reflecting film so that thereflecting film has a shape to control the direction of the reflectedlight.
 5. The luminescent panel according to claim 4, wherein the lenshas a truncated cone portion and a circular cone portion.
 6. Theluminescent panel according to claim 4, wherein the lens has a circularcone shape.
 7. The luminescent panel according to claim 4, wherein thelens has a truncated cone shape.
 8. The luminescent panel according toclaim 4, wherein the lens has a curved surface.
 9. The luminescent panelaccording to claim 1, further comprising a lens array so that the firsttransparent electrode, the luminescent layer and the second transparentelectrode define a plurality of pixels and the reflecting film has ashape to control the direction of the reflected light.
 10. Theluminescent panel according to claim 9, wherein the plurality of pixelsindividually emit the light, and the lens array has a plurality of lensportions each of lens portions corresponding to each of the plurality ofthe pixels.
 11. The luminescent panel according to claim 9, wherein thelens array has a fly-eye lens.
 12. The luminescent panel according toclaim 1, wherein the first transparent electrode, the luminescent layerand the second transparent electrode define a plurality of pixels, andthe transparent substrate has a lens array.
 13. The luminescent panelaccording to claim 12, wherein the lens array has a plurality ofcircular cone shaped lenses.
 14. The luminescent panel according toclaim 1, further comprising a space provided on the inner surface of thereflecting film so that the reflecting film has a shape to control thedirection of the reflected light.
 15. The luminescent panel according toclaim 14, wherein an inert gas is filled in the space.
 16. Theluminescent panel according to claim 1, further includes a transparentresin provided on an inner surface of the reflecting film so that thereflecting film has a shape to control the direction of the reflectedlight.
 17. The luminescent panel according to claim 1, furthercomprising a lens provided on an outer surface of the reflecting film sothat the reflecting film has a shape to control the direction of thereflected light.
 18. The luminescent panel according to claim 1, whereinthe luminescent layer has a plurality of charge transport layers. 19.The luminescent panel according to claim 1, further comprising aswitching element connected to the first transparent electrode for apixel.